This invention relates to an impact absorption apparatus and especially to an energy absorption device for a vehicle bumper impact system.
It is typical for an automotive bumper system to include three key components. The first is a decorative fascia, usually of plastic, mounted on the exterior of the front end module. The second is a rigid impact beam, typically constructed of roll formed or stamped steel. And the third is an energy absorption device connecting the impact beam to the vehicle frame rails. These three components are designed together to meet the performance requirements for low and high speed impacts.
It is beneficial to design the bumper system in such a way that limited damage is transferred to the vehicle frame rails under impact by properly engineering the energy absorption device. One guideline provided for this design process is for the bumper system to have a peak loading capability equivalent to 85% of the combined rail capacity. This assures that the energy absorption unit will crush first upon impact before loading is imparted on the rails. It is also beneficial to design the bumper system to provide this energy absorption in a controlled and repeatable manner. This allows for consistency in vehicle crash behavior.
There is substantial prior art regarding energy absorption units and bumper systems including U.S. Pat. Nos. 5,427,214; 5,732,801; and 4,272,114. These disclosures depict various methods of meeting the energy absorption targets for the bumper system. Shortcomings of these designs include inconsistency in deformation and resultant energy absorption, instability in lateral loading, high associated manufacturing costs, and post impact damage visibility.